hope
spending too much on rocks
Member since May 2008
Posts: 477
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Post by hope on Feb 19, 2009 22:07:22 GMT -5
Hi everybody,
I have been accumulating some slabs that I don't really want to cut into cabs and have been thinking about polishing them whole.
I have been looking at the Lortone, Covington, and RayTech machines in the 16 inch size.
Any first hand accounts of these machines or testimonials.
Hope
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rockhound97058
freely admits to licking rocks
Thundereggs - Oregons Official State Rock!
Member since January 2006
Posts: 760
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Post by rockhound97058 on Feb 20, 2009 0:05:57 GMT -5
I personally run a 20" Lortone Vibra-lap and love it. It's been a work horse for years! I have only had one problem and that was the bearing locked up. The only bad thing about the problem... is Lortone says "you cannot replace the bearings" and wanted me to buy a complete "power head assembly"..... I tore the thing apart and fixed with with a tractor bearing of all things!
Any rate the lortone lap works great! - Now keep in mind though when you purchase a vibra-lap. For slabs you'll need some sort of weight system for the slabs. The heavier the item the better polish it takes. Also keep in mind if you use the vibra-lap with the grinding pan you'll still need to sand the stone before polishing. The only bad thing I've encountered when using the vibra-lap is course grained stones, such as many Thundereggs from central Oregon it seemed to really under cut even with 220 grit. Good solid agates, jaspers ect... work fantastic!
Jason
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highplainsdrifter
fully equipped rock polisher
Member since December 2008
Posts: 1,266
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Post by highplainsdrifter on Feb 20, 2009 12:14:00 GMT -5
I have a 16" Covington that I am very happy with. I've done over 100 slabs on it with no issues. I'm polishing a set of slabs on it now. I also polish slabs on expando drums. For the vibratory lap, here are some pros/cons/tips:
1. Patience is important, especially at the first step. The vibratory lap process takes considerably longer than sanding belts/drums. It is best to pick slabs with minimal saw marks. I start with 80 grit and use the two minute pencil test before moving on. This is the longest step by far. The slab must be sanded very flat on the first step or the subsequent steps will take forever.
2. The vibratory lap requires the least amount of labor. Just put the grit, surfactant, water and weighted slab in and check/clean it occasionally.
3. You need to ensure the slab is weighted down and the edges are protected. I use circular plexiglas pieces with lead weights on top. I keep them overhanging the slab at least 1/2" and attach with 3M double sided foam strips.
4. The lap must be well leveled or the pan will wear unevenly. The slabs must rotate and move around the pan in a circular manner.
5. You'll want to use a cover for the lap to keep it from drying out too quick and to prevent a huge mess. I use pieces of plastic I cut from garbage bags and large rubberbands.
6. Getting a good polish on the lap at the final step can be tricky. I prefer to polish on a suede pad if the slab will fit in my rig.
7. I defintely prefer the look of a flat lap polished slab vs. the drums. They are so much flatter and the reflected light has very little distortion.
Over the last several weeks I've been doing a set of slabs on the flat lap (15 slabs) and a set on my expando drums (~50 slabs). The flat lap slabs are finishing my second grit stage (180 grit) while my expando slabs are almost through my 600 grit stage. For speed, you can see the expandos are better, but for quality IMO the flat lap is best.
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Mudshark
fully equipped rock polisher
Diplomacy is the art of saying 'Nice doggie' until you can find a rock. Will Rogers
Member since December 2008
Posts: 1,083
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Post by Mudshark on Feb 21, 2009 17:13:02 GMT -5
I have a 12 inch Covington and have had no issues with it.It does take a while to go thru the full process so I'm currently building a flat lap with diamond wheels and plan on using the vibe lap for the final polish on the better slabs. Mike
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hope
spending too much on rocks
Member since May 2008
Posts: 477
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Post by hope on Feb 23, 2009 15:48:56 GMT -5
Really great information and I appreciate it all. I have another question(s).
I am reading that the slabs must be able to move around the machine. Does this mean that you can't do just one slab that covers nearly the whole machine? If this is the case, how big, and how many slabs can you do at at time on a 12 inch or 16 inch machine?
Thanks in advance for your time and input,
Hope
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Mudshark
fully equipped rock polisher
Diplomacy is the art of saying 'Nice doggie' until you can find a rock. Will Rogers
Member since December 2008
Posts: 1,083
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Post by Mudshark on Feb 23, 2009 17:01:08 GMT -5
Hope,I have six slabs in my 12 inch machine dancing around right now.All are about 3 to 5 inches.If you are thinking about a 16 inch machine and putting one slab in it that covers most of the lap plate I would really love to see that slab and the saw you cut it on ;D Ok,I just ran out to the shop and pulled 5 slabs out and left one in,it's still moving around but not as fast.The other slabs bumping into it help the pushing action quite a bit.I wish I had a real big slab so I could try it for you but I dont have anything real big at this time.I think they work best when the plate is near full so I think one big slab would do Ok.I'll try to post a pic later tonight of the machine in action. Mike
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Mudshark
fully equipped rock polisher
Diplomacy is the art of saying 'Nice doggie' until you can find a rock. Will Rogers
Member since December 2008
Posts: 1,083
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Post by Mudshark on Feb 23, 2009 18:05:54 GMT -5
Hope,heres a couple pics of my vibe lap.As you can see I dont have any weight on the slabs,I usually do but I took them off after the first two stages.The slabs are in 600 grit in the pics and I just felt like experimenting without the weights in the last two stages to see if there is any difference in the end result.I use plywood disks taped to the rocks and various size plumbing fittings for weights.I should have left the disks on and just taken the weights off.With the disks on I would have one or two less slabs going.It would also be a lot quieter because the rocks are tapping into each other and the racket is driving me nuts.I use regular shower caps for a cover,one for each grit size. Mike
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Post by johnjsgems on Feb 23, 2009 23:49:57 GMT -5
You can make bumper rings out of tubing to place around each slab. That will stop the banging. It also helps prevent the edges chipping. I don't know what maximum size would be on the ones mentioned but Rociprolap says 20" lap will handle 16" pieces.
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hope
spending too much on rocks
Member since May 2008
Posts: 477
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Post by hope on Feb 28, 2009 21:56:49 GMT -5
Thanks everyone for the great info. Those pix are super, Mike. It sure does look like this could get messy. I understand the use of the shower caps.
Hope.
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DeanW
has rocks in the head
Member since December 2007
Posts: 721
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Post by DeanW on Mar 2, 2009 14:30:59 GMT -5
We've been using donuts made from PVC piping instead of the tubing-rings to protect our slabs and chunks. Previous owner of our house left several pieces of 8" and 10" pipe, but I want some larger diameters to use on our 27" laps. Yeah, we do have some slabs up to nearly 20" long that we want to polish.
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